RJC

You're welcome.

I think the 12 E550 coupe was tested a while back in one of the euro car mags and I can't remember which one as I get them all; the car ran about .4 quicker 0-62 vs the '11 if I remember correctly. I don't know why the US mags haven't published any info yet?

nawlinstornado

I'm still somewhat skeptical that these numbers will apply. The base sedan is heavier than the coupe, and the 4matic has even more girth. And while all-wheel drive gives a better 60' time, the unsprung mass will reduce acceleration beyond that point. I've raced plenty of AWD cars that jump faster but I'm flying past them the mid-point.

As to the weight difference, the rule of thumb is .1 second per 100 pounds; the 4matic weighs 4034lbs, the coupe 3773lbs (from MBUSA.com). That's roughly a quarter second just from the weight differential. That narrows the gap to less than .25 seconds between the SL and the E, and none of the tests were conducted on the same track under the same conditions. And remember, again, that the SL has more rubber on the ground (285 vs. 255).

I think it's too close to call. RJC, if you end up buying the SL, let's meet midway and put it to the test. I'll have my wheels and tires by then.

nawlinstornado

I just received a response from my the product design team at RennTech:

RJC

Make of the numbers what you wish. MB caught a lot of flack putting the same powered engine in the E as the S which they've now appropriately rectified.

According to the new Automobile mag the 14 S sedans base V8 will be 510hp and they all get a 20hp increase from hybrid tech.

Lol...I'm way beyond the drag racing days but thanks anyways.

nawlinstornado

I was actually hoping we could eliminate the effect of all the variables by letting me drive your car on the same track and day as mine!

RJC

Lol



Did you guys realize the new SL weighs less than the 550 cab by 113 lbs? 4048 E550 and 3935 for the SL; thats quite a feat considering the SL has more standard equiment which adds hundreds of lbs plus the SL has 20 more hp and about 70 more lb ft if of torque so its power to weight ratio is significant and it darn well should be for $117,000.00!!!! Lol. The SL's extra power and torque should easily overcome the extra 160 lbs of weight vs the coupe; an extra 70 lb ft of trq is a ton let alone the 20 more HP. I do think the E550's offer a tremendous bang for the buck!

nawlinstornado

The horsepower isn't enough alone to overcome the difference, but the torque MIGHT get you there. The question becomes where the power comes in and if there are drivetrain losses due to transmission, program, or *potential* lower body stiffness.


Back on topic:

The real question is whether MB numbers are accurate. It wouldn't be the first time that a manufacturer has given their top-line products an edge on paper. When I had my audio retail store in the 90s, product literature for mid-range products often omitted the advanced capabilities, or "suppressed" real performance specifications, that were prominently featured in their halo devices.

I haven't heard any rebuttal of RennTech's dyno numbers and those are much higher than advertised. But it wouldn't shock me to learn that the difference in OEM specs was created by the marketing department.

I have no doubt that a proud new SL550 owner will take their car to a dyno shop ASAP. When that happens, we'll have some WHP numbers for comparison.

In the meantime, I was already planning to take my car to a dyno shop and get a baseline before mods. At least we'll have a comparison to the RennTech numbers.

BTW, I was serious about wanting to drive your car.

Dueclaws

[quote=nawlinstornado;5227783]I just received a response from my the product design team at RennTech:
[/FONT][/COLOR

Good to see they're working on it. Please keep us posted. Thanks

Great!

nawlinstornado

I found a review of the 2013 SL550 in Motortrend.
http://www.motortrend.com/roadtests/...50_first_test/

It weighs 4104lbs with a 52/48 distribution (f/r). If I remember their testing methodology, they actually weigh the vehicle. MB's "estimated" curb weight is 3935.

FYI

nawlinstornado

This is getting painful:


What the hell?!?!?!

Dueclaws

Nawlins-
That '13 SL is pretty quick at 4 secs 0-60. See if you can beat it after you add the wide tires.
You might want to check reliability on Kleeman's LSD. I've read that the "blocks" wear.

When are you going to dyno your E?
Due

nawlinstornado

I found one test that got 4.5 0-60 in a bone-stock E550 sedan on a track with real measuring equipment. I haven't found a similar track measurement of the SL or the E-coupe.

I've seen the same numbers you posted on the SL, but no commentary on the conditions or measurement process. A lot of those magazine reviewers are lazy and use a stupid gtech on the street. In my experience, they give numbers that are much better than reality.

I haven't seen anything on the subject, but I'll be sure to find out.

I'm planning to do my stock testing this fall. Maryland International Raceway has lots of Test & Tune nights, and I found a dyno tester nearby that is relatively inexpensive. I would do it earlier but we're in the process of moving. I've already made tentative plans with some local friends for the October 12th weekend at MIR. I'll probably do the dyno runs a week or two prior.

Just in case you're wondering, my rough test plan is:
Bone stock: Dyno + drag (1/4 mile, not that wimpy 1/8 mile!)
Plus wheels/tires: drag
Plus LSD: dyno + drag
Plus ECU: dyno + drag
Plus transmission: dyno + drag

I'm not sure about the transmission or ECU just yet. If my dyno numbers are anything like RennTech's, then I may hold off for a bit. Then again, knowing me, I'll get used to the LSD and extra rubber and find myself with a hankering for more power.

I'm doing an extra dyno run after the LSD to see if the rebuild reduces some of the drivetrain losses from the stock setup. Same for post-transmission rebuild, if I actually do it.

nawlinstornado

Screw Motortrend. My 2012 E550C is faster than their 2013 SL550.

See here: https://mbworld.org/forums/e-class-c...-1-4-mile.html

'nuff said.

ronsc1985

Don't get carried away. Unless you know the absolute temperature, the absolute atmospheric pressure and the wind direction it is impossible to make any meaningful comparison.

Btw your best time is about exactly what you should run based on 402 hp, 3930 weight and the atmospheric conditions yesterday. I based this off some data from a 7.50 run on a former race car at the same track with no head or tail wind.

You can scale your results on subsequent days by multiplying the results by the cube root of ((new temp/old temp)*old barometer reading/new barometer reading). You also have to correct for wind conditions.

nawlinstornado

1. Does no one have a sense of humor?
2. Your weight is wrong.
3. Comparison to a 7.5 sec race car is ridiculous. You don't have the same drivetrain losses, traction, etc. Let's not forget about fuel. Temps? What, exactly, are the coefficients of friction for my model/size of tire?

Oh, and do a search for CTS-V 1/4 mile times. They are running 12.5 by owners and have 550 HP.

That other car that I ran with on the timeslip was a heavily modded Camaro SS that dyno'd at 442 at the wheels. Same day, same track, same time.

I recommend taking more factors into account than just barometric pressure.

ronsc1985

Is no one capable of reading? The calculation used both atmospheric pressure and temperature. For your information the type of car makes no appreciable difference unless you can't hook up. It's simply horsepower and weight assuming the car is not a barn door. The listed curb weight for a e550 coupe is 3773. To this you have to add the driver weight and any crap you are carrying in the car. 3930 is a guess at the additional weight.

You can delude yourself all you want about your car having a lot more then the factory rated Hp if it makes you feel better but facts are facts and physics is physics.

BTW a "heavily modded' Camero that can't get into the low-mid 11's is not running very well. People with Z06 corvettes go into the 10's all the time bone stock.

nawlinstornado

Seriously, you just killed your credibility. The new Z06 is a mid-11 car, at best. Most are getting 11.6 to 11.7. There was one at the track yesterday running consistent 11.8s.

I'm not deluding myself about the horsepower in my car. But there are a lot of factors at play besides temps, barometric pressure, etc. How about the torque converter TM value and stall speed? Gear ratio? Unsprung vs. Sprung weight? Weight transfer? Tire type, size, and pressure? Your elementary atmospheric calculation only works with the same car and can't be used to compare cars.

By the way, just got the new Motor Trend mag today. They tested the new 2014 Aston Vanquish with 565 horsepower and ran a 12.3 @116.2. Hell, even Godzilla (GT-R) runs mid-11's.

Again, I'm not claiming I have 500 horsepower. Just that the car, as a system, is well designed and balanced AND can hang with cars having significantly more power.

np888

It's well documented that the E550C is heavily underrated. In fact just about every single dyno done on the car has shown the exact same thing.

Let's not get carried away, you sound like the government, "oh the weather is to blame for these poor jobs numbers blah blah blah". Weather shmeather. He put up 12.5. Deal with it.

And re: CTS-V comment, those things are hardly designed to actually be good at anything, just typical americans throwing horsepower at a car. My old 328i could probably do better than a CTS-V LOL.

nawlinstornado

Try this for an estimate not based on a 7.5 second car:

http://www.dragtimes.com/horsepower-...power+Estimate

nawlinstornado

I just found a measured curb weight for the car, added driver and other crap to the balance, and input it into the same too. Here's what you get:
http://www.dragtimes.com/horsepower-...power+Estimate (yields 466hp)

BTW, weight based on measured car weight plus driver (220) and all my normal gear (38 lbs to round up). I did not take into account fuel weight, by I tanked up 2 runs prior and the needle was still pegged on full.

I don't know exactly how much stock to put in those numbers, but it basically jives with RennTech's dyno numbers (392 horsepower and 441 ft.lbs. torque at wheels). Using those numbers with online tools reveals estimated crank horsepower to be:
http://www.mk5cortinaestate.co.uk/calculator4.php (yields 484hp). I can't find a tool, but a variety of formulas I found online yield 501 to 545 ft.lbs. of torque.

I definitely feel high numbers are over-estimates. But 450-460hp and 515ft.lbs. seems to be a reasonable estimate of the real power put out by the bi-turbo V8. The more I talk to MB people, the more willing I am to accept that 1) all the bi-turbo models are underrated, 2) that they all put down the same power BUT the marketing people wanted to make S/SL/CL/CLS buyers feel like they got more for their money, and 3) any measured performance above the E-class (which I still haven't seen timeslips for) is the result of wider (and sometimes better) tires. They all come with 285s while the E-class arrives with 255s.

Gerry_C

Do the SL or CL come with a form of limited slip in the rear? That could also greatly enhance their performance.

P.S. thanks for adding your time to dragtimes

nawlinstornado

I don't think so. Looks like they use the same "torque vectoring" through ABS that the E550 uses. I'm guessing MB saves the LSD for AMG vehicles only.

It was kind of fun, so happy to do it.

BTW, check out: https://mbworld.org/forums/e-class-c...rs-wanted.html. Now that Quaife is finally producing an LSD for the E550C, that's my next upgrade.